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Friday, February 26, 2010

Does race have anything to do with PJS?

PJS seems to affect people of all races and in all regions of the world.

For many years, I've been wondered whether PJSdisproportionately affects people of any race. For answers, I first studied the medical literature (websites, journal articles and text books), then personal stories of PJS people around the world. Many years
ago a young African-American woman with PJS and I exchanged emails. She'd
had a rough time with PJS and I've since remembered her statement, "Life is
hard enough already and this isn't making it any easier." This further
sensitized me to how race affects medical care and access to care and even the
case reports written by doctors.

Genetically speaking, PJS is a single-gene autosomal dominant genetic
disorder. I'll define each of these terms in simple English. A single-gene
disorder usually leads to the traits (in our case spots, gi & nasal polyps, cancer risk,
genital tract tumors), while most diseases are considered polygenic (many genes)
and environmentally & lifestyle influenced. Autosomal means that it is not
sex-linked like some other genetic disorders. Dominant means that only one
copy of the gene for that trait is present (you get one copy each from
bio-mom & bio-dad).

In PJS a mutation of a single gene on chromosome 19 (LKB1/STK11) leads toPJS traits. The mutation can be something new that happens at or shortly
after conception. For example, I'm the first person in my family with PJS -
I'm said to have a sporadic or denovo mutation. If I'd had children, each
child would have a 50-50 chance of having PJS. This is like flipping a coin -
you could get a run of heads or tails. It's possible to have all, some or no
affected offspring.

PJS is considered to be highly penetrant. This means, if you have the
mutation, you should have the traits. The literature says so. But many examples
from the PJS Online Support Group say otherwise. There are family members with AND without spots, polyps, cancer and other PJS-related traits. A parent might have an
affected sibling and affected offspring, but seem to be fine. There is another
recently reported genetic oddity in PJS called mosaicism. I won't go into this
now, but it means that someone can have PJS in just certain parts of their
body.

So, the mutation that leads to PJS can happen at or shortly after
conception and that mutation can be passed on to offspring. It isn't related to race,
but to having the genetic mutation or defect.

Does race play a role? With one exception, I don't think so. There have
been reports of PJS from every continent and almost every country. People from
many regions and many ethnic backgrounds have written to me one-to-one.
Because this is a primarily English speaking/reading/writing group, we don't
hear often from those whose second, third or fourth language is English. But
we've had members in Asia, South America, the Middle East and Africa as well
as North America, Australia and Europe.

I didn't take the time to review the medical literature, but
remember many case reports from around the world of PJS affecting people from
different ethnic groups and races.

My one exception to the race question? It's possible that one person withPJS would have many children who would have many children. One promiscuous
man or fertile female could conceivably (pun intended) produce generations
of affected offspring. This happened in Venezuela with another autosomal
dominant genetic disorder called Huntington's Disease. One woman who lived in
the 19th century passed on the trait to over 14 thousand offspring in 10
generations. (http://www.pnas.org/content/101/10/3498.full). I haven't read
about this happening in PJS, but it may be possible.